This part of ISO 12640, according to an NPES press release, provides a reference set of wide gamut display-referred color images in electronic form, encoded as 16-bit Adobe RGB (1998) digital data, that can be used to evaluate changes in image quality during coding, image processing (including color re-rendering and color space transformations, compression and decompression), displaying on a color monitor and printing. The images of Part 4 supplement the images of Part 1 (CMYK data), Part 2 (sRGB gamut images), and Part 3 (large gamut images encoded as CIELAB data). Part 4, available on DVD, includes 14 natural images and two synthetic images (test charts).